I am honestly so blown away by how polished this is. It's hard to believe that this game only took one week because it really looks like a game I could go and buy on the App Store right now. I love the simple and round art direction, and I'm in love with the animated background as well. The thing that stood out to me the most is definitely the sound design. The fact that you were able to match the music with the actual gameplay so well is amazing. I especially love it when the beat drops and three more circles come into the screen. Oh MAN does it get me pumped.
This game is damn near perfect, but if I were to point out a couple of nitpicky things, it would be:
1) Having the obstacles disappear when they are right in front of the player feels a bit strange. I understand that the obstacles do not harm you when they are disappearing, but it still gives me a slight jolt when it happens, and I think players would have a more comfortable experience if the obstacles just disappeared when the player was on the other side of the circle.
2) I don't know if this is a bug or if it's intentional, but when you die while the three other circles are on screen (when the bass drops), all of the circles stop spinning except the bottom left one. Is it supposed to be the only one left spinning? It felt a bit strange but it's honestly such a small thing that I wouldn't care if you left it as it is.
3) I kinda wish you started the song at the same time at the beginning of every round. I know it might be hard to do cuz of how well the sound is mixed in with the gameplay, but I think having audio cues to know how far you are in your run would be helpful. During my playthroughs, the bass drop could happen before the 10 second mark, or it could happen near the 50 second mark. It would be nice to have it always happen at the same time so I could be like "Oh I hear the bass drop! Now I know I'm past the 30 second mark" or something like that without having to constantly glance at the timer to check up on how well I'm doing.
I think that's about it, but even while writing this, I can't stop thinking about how good this game is! Please release this on the App Store asap cuz I am so ready to buy it. Phenomenal job!
Also, if it is okay for me to ask, what song did you use for this game?